JPS6180246A - Positive resist material - Google Patents

Abstract

PURPOSE:To prevent a negative inversion in an eye-fitting mark scanning part by applying the positive resist contg. a mixture of an alkaline soluble resin and a quinoediazide compd. or 2-methyl-pentene-1-sulfone to the material. CONSTITUTION:A novolak resin containing e.g. O-(tertiarybutyl)phenol-O-cresol- formaldehyde is used as the alkaline soluble resin. For example, naphthoquinone (1,2)-diazide(2)-5-sulfone-P-methylphenol ester is used a the quinonediazide compd. The titled material is prepared from the mixture of the above described novolak resin and the above described azide compd. or the above described sulfone. The ratio of between an exposure (DP) in a formation of a positive pattern and an exposure (DN) in an occurrence of the negative inversion is >=50 (DN/DP). As the above described positive resist is used to the titled material, the mark scanning part does not occur the negative inversion, and said positive resist may be stripped by the solvent.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to positive resist materials used in the manufacturing process of semiconductor devices, magnetic bubble devices, etc. [Prior Art] Currently, semiconductors are produced by direct writing using ionizing radiation. In the process of manufacturing devices, a resist material is applied onto a substrate on which alignment marks are formed, a charged beam is scanned to detect the alignment marks, the position is set, and then exposure is performed. It is used in the process of forming a resist image at a desired location by developing it. Therefore, m
In the manufacture of semiconductor devices and the like by direct writing using an s-ray set, the process of forming this resist pattern is a very important process.

In the resist pattern formation process, positive resist and negative resist are used depending on the exposure area ratio and processing conditions of the underlying substrate. For example, in the process of forming contact holes, a pattern forming method using a positive resist is a very complicated method and is widely used.

[Problems with conventional technology]

Conventionally, in the pattern forming method by electron beam direct writing, a mixture of a cresol-formaldehyde-based novolak resin and a quinonediazide metal or 2-methylpentene-1-sulfone has been used as a positive resist. An example of such a positive resist is Shipley's Microposit.

series, Tokyo Ohkasha's 0FPR series, and Hitachi Chemical's Raycast. However, the process using such a positive resist requires scanning a charged particle beam when detecting alignment marks, which causes a crosslinking reaction at that location and gels, causing negative reversal and making it difficult to peel off. This poses a problem in that it has a significant negative impact on subsequent steps.

Currently, this problem is avoided by removing the portions that cannot be removed by ashing with oxygen, but the damage to the device due to ashing cannot be ignored.

[Purpose of the invention]

The present invention has been made to solve the problem described in -E, and provides a positive resist material useful for direct writing using ionizing radiation.〇 [Configuration of the Invention] Positive resist material of the present invention is an alkali-soluble resin and a quinonediazide compound or 2-methylperetene-1
- Comprising a mixture of sulfones, and the amount of exposure when forming a positive pattern.

and the exposure amount that causes negative reversal, the ratio D N / D P
It is a positive resist characterized by having a value of 50 or more.

[Detailed explanation of configuration]

Detection of alignment marks by scanning ionizing radiation is an indispensable process in the phosphorography technology used to fabricate semiconductor devices and the like. In particular, in the case of electronic green exposure, it is desirable to keep the column conditions fixed in order to achieve high accuracy in detecting alignment marks, so the alignment mark is detected while scanning the electron beam using an exposure meter when forming a positive pattern. Since such scanning is normally performed approximately 50 times, the mark detection portion of the positive resist used becomes gelled and cannot be peeled off. Therefore, ashing with oxygen,
It was necessary to remove it by immersing it in a strong acid such as sulfuric acid in a heated peeling solution.However, this can be prevented by setting the exposure amount DN at which the positive resist gels to DN/DP≧50.0 As a result of intensive research, the inventors revealed that the reaction between the quinone diazo group, which is the first curtain, and the base resin can be ignored, and that there is no correlation between DN and DN. Therefore, it has been found that by selecting the photosensitizer and the base resin, it is possible to obtain a positive resist having a ratio of DN (D)J/np of 50 or more. -Also, by coating a resist material on the substrate and detecting alignment marks, the resist film is exposed by irradiating ionizing radiation at the desired location, and then developed. In the pattern forming method for forming a positive resist image, if a positive resist with DH/Dp≧50 is used as the resist,
It was also found that the alignment mark part could be easily peeled off, and subsequent treatments such as ashing with oxygen were not necessary.

30% by weight of photosensitizers A and B having non-diazo groups and a m-cresol novolac resin as a base resin were mixed and dissolved in diosan to make a 20% solution. This solution was applied to a silicon wafer by spin coating and baked at 80°C for 30 minutes to a thickness of approximately 5 mm.
Resist of The same exposed film was immersed in tetrahydrofuran for 90 seconds to determine the exposure dose DN at which an insoluble portion was formed. Second
As shown in the figure, when A, which is a difunctional group, and B, which is a monofunctional group, are added, the reaction between the quinone diazo group, which is a sensitive group, and the resin does not occur, although the sDN is almost the same as the DN of the base resin. When OC゛, which is known to be absent, is added, the size is slightly smaller, but this is due to the reaction between the resin and other places than the quinone diazo group. %A# for DP
There was no change when B# and C were added. This shows that the reactivity of the quinone diazo group is the same for the cases of % Aj Bj and C. Therefore, as seen in this example, there is a difference between the reactivity of the quinone diazo group determining the DP and the DN in the positive resist. There is no correlation. Therefore, by selecting the base resin, s DN'
/Positive resist with Dp≧50 is possible. An example of this is shown in the following example.

(Example 1) In order to increase the DN, it is generally necessary to lower the molecular weight, but if the molecular weight is small, the film forming ability is poor, and the performance as a positive resist is slightly inferior. Therefore, it is best if gelation due to crosslinking reaction can be suppressed without reducing the molecular weight.

As a result of intensive studies, the inventors of the present invention discovered the general formula (m, n
It has been discovered that the novolak resin, which can be expressed as (represents a positive integer), is not easily soluble in an alkaline aqueous solution, which is a developer, but is less prone to crosslinking reactions than ordinary novolac resins. In addition, such a novolak resin is used as a base resin, and a quinone diazitome compound or a 2-
Positive resists made of mixtures using methylpentene-1-sulfone etc. are difficult to cause crosslinking reactions <Da/D
If p≧50 is satisfied, the part irradiated with charged particles during alignment mark detection does not gel and can be easily peeled off, but the base resin is easily soluble in an alkaline aqueous solution. It became clear that the conventional function as a positive resist was not impaired.

It has been pointed out by L Re Fahren holtz that the presence of spatially large groups such as propyl, butyl, and phenyl groups has the effect of suppressing crosslinking reactions [Journal of Vacuum Science]・And Technology (, r.

Vaj, 8ci, Technol, 19(4), 11
11 (1981). ]0 However, as a result of study by the present inventors, it was found that if the substituent is a spatially large group, it is extremely difficult to dissolve in an alkaline aqueous solution, which is a developer, and cannot be used in practice. In addition, the present inventors have found that the reaction between the quinone diazo group, which is a photosensitizer, and the novolac resin does not contribute to crosslinking, but 8°Re Pahrenhol
tz does not mention this, and the present invention is not subject to any restrictions.

Next, a concrete example will be shown.

Ortho(tertiary butyl)phenol 59° orthocresol 4g and 35% thiformaldehyde aqueous solution 5.
8 g was placed in a flask, 0.89 g of a 35% aqueous hydrochloric acid solution was added as a catalyst, and the mixture was reacted at 120° C. for 1 hour. Thereafter, the reaction product was reprecipitated with water to obtain 5 g of white solid. The resulting novolac resin consisting of ortho(tert-butyl)phenol-orthocresol-formaldehyde has a structure confirmed by NMR (Nuclear Magnetic Resonance Spectrum) (cDcz, medium) δ(
ppm): 1. a3(-c(cHa)'s)2.13
(-CB, ) 3.80 (-CH,-) 6.67-7.0 (04) Composition ratio: Ortho (tert-butyl) phenol 0.53: ortho-cresol 0.47 This resin was converted into ethyl cellosolve acetate. Dissolve in 20
wt% solution and applied to a silicon wafer at 3000 rotations/
A thin film with a thickness of 8000X was obtained by spin coating at 90℃ for 30 minutes and baking at 90℃ for 30 minutes.When this film was irradiated with an electron beam and the exposure amount at which the polymer became insolubilized was measured, it was 3X.
It was 10-3C/cm2. 30 wt% of naphthoquinone (L2) diazide (2)-5-sulfonic acid-paramethylphenol ester was added to the same resin as a photosensitizer.
It was mixed and dissolved in ethyl cell solve acetate to make a resist solution.

This solution was spin-coated on a silicon wafer and baked at 80°C for 30 minutes to obtain a resist film with a thickness of 6000X.The resist film was irradiated with a zero electron beam and developed with an aqueous sodium hydroxide solution with an exposure dose of 03. A 0.5 micron line-and-dew space was resolved with a sensitivity of 20 μC/cIn2. Gelled Marusekou lid f, according to my research,
Almost the same as before adding the photosensitizer, 3 x 10 C/
was a sword ◎D8, the ratio is D N/D p = 1
It is 50. As a reference example, the DN of a general positive resist is shown in FIG. D N/D p is approximately 20.

(Reference Example 1) Using the same method as in Example 1, ortho (tertiary butyl) phenol novolak jugeji and para (tertiary butyl) phenol novolac resins were synthesized. When the exposure amount for gelling with electron beam irradiation was investigated, the ortho-substituted product was 5 X 10-30 C/lx2, while the para-substituted product was 3 X 10-3 C/lx2. However, these were extremely poorly soluble in a 1N aqueous alkaline solution.

In the resin used, the component ratio of tertiary butylphenol is preferably 0.2 to 0.8. If the component ratio of tertiary butylphenol is 0.2 or less, the effect of suppressing the crosslinking reaction is small; This is because it becomes extremely difficult to dissolve in an alkaline aqueous solution. The amount of the photosensitizer to act as a positive resist is preferably 20 to 40 wt% in the case of a quinonediazide compound, and 10 to 30 wt% in the case of 2-methylpenten-1-sulfone. This is because if the amount of the photosensitive agent is too small, the dissolution inhibiting ability will be weak and it will not function as a positive resist, and if the amount of the photosensitive agent is too large, the sensitivity as a positive resist will decrease.

Furthermore, as a result of examining the positions of the substituents, the present inventors found that ortho-substituted products have a greater effect of suppressing the crosslinking reaction than other substituents. Therefore, the most preferred position of the substituent is the ortho position.

(Reference Example 2) Cresol Nogilac resin with ortho-, meta-, and rose-substituted products was synthesized and the exposure amount for gelation was examined. I found out that I have a good body. Among these resins, those with low molecular weights had poor film-forming properties and could not be used as base resins for positive resists.

(Example 2) 19 wt% of 2-methylpentene-1-sulfonic acid was mixed with the novolak resin described in the matrix forming step, and dissolved in isoamyl acetate to obtain a 5 wt% resist solution. When we conducted an experiment similar to Example 1 using this resist solution, we found that 0.5 micron lines and spaces were resolved at 10 μC/cIn2, and the exposure amount for gelation was 3, the same as before adding the photosensitive agent. ×1O-3C/cln
It was confirmed that the desired DN/D = 300) 50 was achieved in 2 (Example 3) Ortho (tertiary butyl) phenol, phenol,
A novolak resin composed of ortho(tert-butyl)phenol-phenol-formaldehyde was synthesized using 100% and formaldehyde with hydrochloric acid as a catalyst.The 0 structure was confirmed by NMR and 90NMR (in CDCjs)' (ppm) ': 1-30 (-C(
CHs) a ) 3.90 (CHt ) 6.67-7.20 (@H) Composition ratio: Ortho (tert-butyl) phenol 0.33: Phenol 0.67 This resin and 2-methylpentene-1-sulfone When an experiment similar to Example 1 was conducted using a mixture of
It showed a resolution of 0.3 microns at a sensitivity of /ex''.The exposure amount for gelation was 1.5 x 10-3C/l11.
2 was the same as before adding the photosensitizer (Example 4)
) Naphthoquinone <112) diazide (2) as the novolac resin and quinone diazide compound used in Example 3
A resist solution was prepared by dissolving a mixture of -5-sulfonic acid-parahydroxybenzophenone ester (30 wt'iJ) in ethyl cellosolve acetate, and the sensitivity was measured by zero electron beam exposure. resolved the lines and spaces. The exposure amount for gelation was 1X10C/i.

(Example 5) As a result of intensive studies, the inventors of the present invention found that the novolac resin, which can be expressed by the general formula (m and n represent positive integers), is easily soluble in an alkaline aqueous solution as a developer. It has been found that not only this, but also that crosslinking reactions are less likely to occur compared to ordinary novolac resins. In addition, a positive resist made of a mixture using such a novolac resin as a base resin and a quinone diazide compound or 2-methylpentene-1-sulfone as a photosensitizer is difficult to cause a crosslinking reaction < DN/D
? ≧50, the part irradiated with charged particles during alignment mark detection can be easily peeled off without gelation, and the base resin is easily soluble in alkaline aqueous solution, making it a positive resist. It has become clear that the conventional functions of the system will not be impaired.

This will be specifically explained below using an example.

Ortho-phenylphenol 5g, ortho-cresol 3.
1g and 35% formaldehyde aqueous solution 4.59 were put in a flask, and 0.89
In addition, the 0-color reaction product reacted at 120° C. for 1 hour was also reprecipitated with water to obtain 59 Shirashi solids. The resulting novolak resin consisting of ortho-phenylphenol-orthocresol-formaldehyde was analyzed by NMR.
The structure was confirmed.

NMR (Nuclear Magnetic Resonance Spectrum) (CDCj, middle) δ (
ppm): 2.13 (-C)(3)3
．． 80 (-CH,-) 6.67-7.5 (αH) Composition ratio: Ortho phenylphenol 0.53: Ortho (17) Tsucresol 0.47 Dissolve this resin in ethyl cellosolve acetate and make 20
wt% solution and applied to a silicon wafer at 3000 rotations/
A thin film with a thickness of 8000× was obtained by spin coating for 30 minutes and baking at 90° C. for 30 minutes.

When this film was irradiated with electronic green light and the exposure amount at which the polymer became insolubilized was measured, it was 5 x 1 O-3C/crn2.

This novolac resin was mixed with 30 wt % of naphthoquinone (1,2) diazide (2) -5-sulfonic acid-halamethylphenol ester as a quinone diazide compound and dissolved in ethyl cellosolve acetate to prepare a resist solution. This solution was spin-coated on a silicon wafer and baked at 80°C for 30 minutes to obtain a resist film with a thickness of 6000X.When developed with a sodium hydroxide aqueous solution with an exposure dose of 0.3N by irradiation with zero electron beam, it was found to be 20μC/ cm
It resolved lines and spaces of 0.5 microns with a sensitivity of .

I also investigated the exposure amount for gelation, and found that it was the same as before adding the photosensitizer (5X 10-3C/cm2 and the jib was 0.2 to 0.
．． 3 is desirable. The component ratio of phenylphenol is 0.
If it is 2 or less, the effect of suppressing the crosslinking reaction is small, and if it is 0.
This is because when the number is 8 or more, it becomes extremely difficult to dissolve in an alkaline aqueous solution. In addition, in the case of a quinonediazide compound, the amount of the photosensitizer to act as a positive resist is 20 to 4
0 wt%, and in the case of 2-methylpentene-1-sulfone, 10 to 30 wt% is desirable. This is because if the amount of photosensitizer is too small, the dissolution inhibiting ability will be weak and it will not function as a positive resist, and if the amount of photosensitizer is too large, the positive resist and the ortho-substituted product will undergo a crosslinking reaction compared to other substituted products. We found that it has a great suppressive effect. Therefore, the most preferred position of the substituent is the ortho position.

(Reference Example 3) Metaphenylphenol-novolac resin and paraphenylphenol novolak resin were synthesized using the same method as in Example 1. ◎The exposure amount for gelation with electron beam irradiation was investigated. The sandwich body is 7
For X10 C7cm, rose substitution product is 6X10-
However, all of these were extremely poorly soluble in l normal aqueous alkaline solutions.

(Example 6) A resist solution was prepared by mixing 19 wt% of 2-methylpentene-1-sulfone with the novolak resin used in Example 1 and dissolving it in in-amyl acetate to make a 51v 1% resist solution. When I conducted an experiment similar to Example 2, I was able to resolve lines and spaces of 0.5 microns at 10 μC/ltn, and the exposure amount for gelation was the same as before adding the photosensitizer, at 5×10 C7 cm (4)
It was.

(Example 7) A novolak resin composed of ortho(phenyl)phenol-7enol-formaldehyde was synthesized using ortho-phenylphenol, phenol, and formaldehyde with hydrochloric acid as a catalyst. The structure is NMI
Confirmed by t.

NMR (CDC/, medium) δ (ppm): 3.90 (C Pigeon)
6.67-7.50 (@H) Composition ratio: Ortho (tert-butyl) phenol 0.3.3: Phenol 0.67 Using a mixture of this tree H and 2-methylpentene-1-sulfone, When an experiment similar to Example 2 was conducted, 30μ
It showed a resolution of 0.3 microns at a sensitivity of C/12 ◎ The exposure amount that still causes gelation was 5 x 10 C/I2) It was the same as before adding the photosensitizer (Example 8) Naphthoquinone (l, 2) diazide (2) -5 as the novolak resin and quinonediazide compound used in Example 7
A mixture of -sulfonic acid-parahydroxybenzophenone ester (30wt96) was dissolved in enalcelsolp acetate to prepare a resist solution. When sensitivity was measured by electron beam exposure, lines and spaces of 0.5 microns were resolved at 20 μC/an. Also, the exposure amount for gelation is the same as when no photosensitizer is added, 5 x 10
"-" It was 07cm2.

〔Effect of the invention〕

As mentioned above, alkali-soluble resins and quinonediazide compounds or 2-methylpentene''l-
A positive resist made of a mixture of sulfones, and characterized in that the exposure amount DP when forming a positive pattern and the amount of light that causes negative reversal 1) The ratio D N /'D of N is 50 or more. Since the alignment mark scanning part does not cause negative reversal, it can be removed with a solvent9.
Therefore, the positive resist material of the present invention and the pattern forming method using the same are useful in the manufacturing process of semiconductor devices, etc., since they have the effect of eliminating the need for subsequent treatment such as ashing with an acid system.

[Brief explanation of the drawing]

Figure 1 is a diagram comparing the DP and DN of the positive resist used in this patent and a general positive resist. Figure 2 shows the DP and DN of mixtures of various photosensitizers and cresol novolac resins. It is a diagram.

Claims (1)

[Claims] It is composed of a mixture of an alkali-soluble resin and a quinone diazide compound or 2-methylpentene-1-sulfone, and the exposure amount D when forming a positive pattern.
Ratio D_N/D_ of _P and exposure amount D_N that causes negative reversal
A positive resist material characterized in that P is 50 or more.